Last month, in response to a lawsuit filed on July 10 by a group of scholars and writers called Citizens Defending Libraries, the library agreed not to start construction until at least October. The library is seeking to have both lawsuits dismissed from the New York State Supreme Court in Manhattan.

The July 10 suit argued that the Fifth Avenue building was originally intended to house a permanent research collection, and that removal of books to off-site storage constituted a violation of the conditions under which the New York Public Library was formed in 1895.

The library’s response calls the plaintiffs’ claims “ludicrous and misleading,” and as proof offers a library trustees’ bulletin from 1897 describing the trustees’ intention for the Central Library to house both a circulating library and a research collection.

David Rubinstein, an attorney for the plaintiffs, said: “We can see that there are significant problems with their submission.”

The planned renovation of the Stephen A. Schwarzman building would remove seven levels of book stacks that until March held millions of volumes from the research collection. In their place, the library plans to construct a new circulating library, replacing the Mid-Manhattan Library as well as the Science, Industry and Business Library.

Library officials have said their plan would solve a number of problems for the institution by replacing a deteriorating branch library, creating safer storage space for books and generating more revenue for staff and book acquisitions.

The library applied in May and June for a dozen permits from the city for what officials described as preconstruction work related to the renovation.

Officials have said in court that the work won’t begin until the completion of an environmental review by the city, now under way. In its court filing Friday, the library estimated that a further six-month delay caused by a lawsuit would increase the cost of the project by about 2%, or “many millions of dollars.”

The library Friday also served the plaintiffs of the first lawsuit with a response that hasn’t yet been filed in court. The first suit was filed July 3 by a separate group of scholars and preservationists going by the name NYC Libraries Legal Defense Committee, although they are not listed under that name on the lawsuit.

Among the legal arguments the July 3 lawsuit presented: that the removal of the stacks would impinge on the public’s right to receive information under the First Amendment.

In response, the library argues: “There is no constitutional right to receive library books quickly or to dictate where a library stores its books.”